1. Field of the Invention
The present invention relates to fluid pumping equipment. More particularly, the present invention relates to a housing for a fluid pump which incorporates a novel pump float cable clamping device. The cable clamping device is capable of manually receiving or releasing the cable without the use hand or power tools.
2. Background of the Invention
A wide variety of fluid pumps and fluid pump housings have long been known in the art. One particular style of fluid pump which is generally intended to be permanently or semi-permanently mounted within a shallow pit or sump, has become commonly known as a sump pump.
Sump pumps are utilized for many applications, which may be of long or short term duration. These applications include contingent-type emergency service as well as normal intermittent or continuous operation. Although many prior sump pumps have been designed which are intended to be controlled manually, it has generally been found more effective to provide a switching device which automatically turns the sump pump on and off as required. The automatic switching device is commonly provided integral with or as an appendage to the sump pump.
Several types of automatic power switches have been provided with sump pumps. Particularly successful prior art pump switches include ball floats which are connected to a rod mechanism pivotally attached to the pump housing. The mechanism is such that the rod pivot shaft switches the pump on when the ball float has reached a predetermined level.
A second pump switch has been provided by a floatable motor shell or housing. The motor housing rises and falls with the liquid level and thereby activates a switch which operates the pump. Another type of sump pump switch is provided by an automatic pressure switch. These pressure switches are generally located in cavities. The cavities fill with fluid, and the fluid applies pressure to the switch to energize the pump.
Another type of sump pump switch is provided by an adjustable float tethered to the sump pump housing. A float is used which is similar in appearance to a conventional ball float. However, the switching mechanism is generally contained within the float housing. Instead of a rigid ball float rod, the switch float is connected to the sump pump by a flexible multistrand cable or tether. Conductor elements extend through the cable from the switch inside the float to pump motor. Unlike rigid ball float rod operated sump pumps, where the changing attitude of the connecting rod operates the switch, the float switch sump pump is turned on and off by the specific attitude of orientation of the switch float housing. The switch float attitude of orientation is dependent upon cable length and fluid depth, whereby the force applied to one end of the float housing by the taut cable as the float reaches the upper and lower limits of its intended travel causes the float to tilt and activate the switch inside as the float attitude changes.
Therefore, it is seen that the level of water required to acheive a switch float attitude orientation sufficient to turn the switch float on and energize the sump pump is determined by the length of the multistrand cable or tether which extends between the switch float to the sump pump. Accordingly, sump pumps can be provided with switch floats which adjustably respond to, and thereby control, different water levels by lengthening or shortening the multistrand cable. Use of a cable clamp allows the effective length of the cable to be varied by changing the point at which the cable is attached to the housing.
A variety of multistrand cable clamps have been previously used. Generally, a fixed length of multistrand cable is provided and the cable is releasably tethered to the sump pump at any desired location along the cable. The cable is tethered by the cable clamp, which is itself fixed to the sump pump. The cable tethering or clamping structures previously used include a "hairpin" type structure. The hairpin provides two generally parallel elongated members which are joined together at one end by a loop, and a tightening device to tighten the two elongated members together around the cable. Generally a bolt and nut assembly is used as a tightening device. The multistrand cable is passed through the hairpin loop connecting the elongated members. The hairpin/bolt assembly is then tightened with tools such as a screwdriver and pliers until the hairpin loop is closed around the cable, securing it in place.
Another method of adjustably securing the multistrand cable to the sump pump housing uses a device known as a "pigtail". A pigtail is constructed from a flexible piece of spring steel or alloy which has been bent into a widely spaced helix. One end of the coiled helix includes a straight piece of spring steel which extends radially from the helix and is attached to the pump housing. The internal diameter of the helix coil is slightly less then the external diameter of the multistrand cable, while the axial spacing between the helical coils is slightly greater than the external diameter of the multistrand cable. Therefore, the multistrand cable is attached to the sump pump housing by the pigtail device at any desired location by tangentally feeding the cable into the spaces between the helical coils serially from one end of the pigtail to the other.
These prior art cable retention devices have inherent design flaws which preclude, to some extent, their usefulness for their intended function. Hairpin type devices generally require hand or power tools to loosen the bolt and nut assembly which secures the hairpin loop around the multistrand cable. The use of such hand or power tools is particularly cumbersome where the sump pump is totally submerged in the liquid medium which level the pump is controlling. Hairpin type devices also tend to permanently deform the cable housing. Although removing a cable from the pigtail does not require tools, it is obvious that "unfeeding" the cable from the helical loops is a laborious act which requires significant time, particularly as to submerged sump pumps. This is also true of removing the cable from the hairpin loop.